Optical Circuit Switches (OCSs) allow programmable control over physical connectivity at a lower level of a multi-level network topology. Using the OCS, the topology can be adapted dynamically to improve network performance by adjusting topology based on demand, traffic patterns, etc. During the transition from one topology to another, packets can be dropped by switches. For example packets are dropped by a switch because they were forwarded to a switch which does not have a valid route to the destination and drops it. According to another example, packets are dropped by the OCS if a mirror is rotating when packet arrives. Packets may also be dropped by a switch because of queue overflow.